Touch scrolling in list picker shouldn't close the popup

Source/web/resources/listPicker.js

 "use strict";
 // Copyright (c) 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 var global = {
     argumentsReceived: false,
     params: null,
     picker: null
 };
@@ skipping 36 matching lines @@
     this._element.appendChild(this._selectElement);
     this._delayedChildrenConfig = null;
     this._delayedChildrenConfigIndex = 0;
     this._layout();
     this._selectElement.addEventListener("mouseup", this._handleMouseUp.bind(this), false);
     this._selectElement.addEventListener("touchstart", this._handleTouchStart.bind(this), false);
     this._selectElement.addEventListener("keydown", this._handleKeyDown.bind(this), false);
     this._selectElement.addEventListener("change", this._handleChange.bind(this), false);
     window.addEventListener("message", this._handleWindowMessage.bind(this), false);
     window.addEventListener("mousemove", this._handleWindowMouseMove.bind(this), false);
-    window.addEventListener("touchmove", this._handleWindowTouchMove.bind(this), false);
-    window.addEventListener("touchend", this._handleWindowTouchEnd.bind(this), false);
+    this._handleWindowTouchMoveBound = this._handleWindowTouchMove.bind(this);
+    this._handleWindowTouchEndBound = this._handleWindowTouchEnd.bind(this);
+    this._handleTouchSelectModeScrollBound = this._handleTouchSelectModeScroll.bind(this);
     this.lastMousePositionX = Infinity;
     this.lastMousePositionY = Infinity;
     this._selectionSetByMouseHover = false;
 
     this._trackingTouchId = null;
 
     this._handleWindowDidHide();
     this._selectElement.focus();
     this._selectElement.value = this._config.selectedIndex;
 }
@@ skipping 28 matching lines @@
 
 ListPicker.prototype._handleMouseUp = function(event) {
     if (event.target.tagName !== "OPTION")
         return;
     window.pagePopupController.setValueAndClosePopup(0, this._selectElement.value);
 };
 
 ListPicker.prototype._handleTouchStart = function(event) {
     if (this._trackingTouchId !== null)
         return;
+    // Enter touch select mode. In touch select mode the highlight follows the
+    // finger and on touchend the highlighted item is selected.
     var touch = event.touches[0];
     this._trackingTouchId = touch.identifier;
     this._highlightOption(touch.target);
     this._selectionSetByMouseHover = false;
+    this._selectElement.addEventListener("scroll", this._handleTouchSelectModeScrollBound, false);
+    window.addEventListener("touchmove", this._handleWindowTouchMoveBound, false);
+    window.addEventListener("touchend", this._handleWindowTouchEndBound, false);
+};
+
+ListPicker.prototype._handleTouchSelectModeScroll = function(event) {
+    this._exitTouchSelectMode();
+};
+
+ListPicker.prototype._exitTouchSelectMode = function(event) {
+    this._trackingTouchId = null;
+    this._selectElement.removeEventListener("scroll", this._handleTouchSelectModeScrollBound, false);
+    window.removeEventListener("touchmove", this._handleWindowTouchMoveBound, false);
+    window.removeEventListener("touchend", this._handleWindowTouchEndBound, false);
 };
 
 ListPicker.prototype._handleWindowTouchMove = function(event) {
     if (this._trackingTouchId === null)
         return;
     var touch = this._getTouchForId(event.touches, this._trackingTouchId);
     if (!touch)
         return;
     this._highlightOption(document.elementFromPoint(touch.clientX, touch.clientY));
     this._selectionSetByMouseHover = false;
 };
 
 ListPicker.prototype._handleWindowTouchEnd = function(event) {
     if (this._trackingTouchId === null)
         return;
     var touch = this._getTouchForId(event.changedTouches, this._trackingTouchId);
     if (!touch)
         return;
     var target = document.elementFromPoint(touch.clientX, touch.clientY)
     if (target.tagName === "OPTION")
         window.pagePopupController.setValueAndClosePopup(0, this._selectElement.value);
-    this._trackingTouchId = null;
+    this._exitTouchSelectMode();
 };
 
 ListPicker.prototype._getTouchForId = function (touchList, id) {
     for (var i = 0; i < touchList.length; i++) {
         if (touchList[i].identifier === id)
             return touchList[i];
     }
     return null;
 };
 
@@ skipping 261 matching lines @@
     }
     this._applyItemStyle(element, config.style);
 };
 
 if (window.dialogArguments) {
     initialize(dialogArguments);
 } else {
     window.addEventListener("message", handleMessage, false);
     window.setTimeout(handleArgumentsTimeout, 1000);
 }